Researchers at the University of Chicago recently completed a study which shows that wealthy white women are the most likely to get a good night’s sleep. The study, published in the July issue of the American Journal of Epidemiology, recorded the amount of time participants spent in bed as well as the time they actually slept.

The results showed that white women get an average of 6.7 hours of sleep per night. White men sleep just over six hours. Black women average 5.9 hours of sleep each night whereas black men are asleep only 5.1 hours per night. Black men took an average of 36 minutes to get to sleep once they were in bed. White women fell asleep in 13 minutes.

Income explains part of the racial difference. Researchers found a direct correlation with total sleep time and the time it took to get to sleep and family income. The more money people make, the easier it is for them to sleep. Low-income people may have more worries which keep them awake and they are more likely to live in congested, noisy neighborhoods which make it difficult to fall asleep.